Brazilian wandering spider: Where are they from and how deadly are they?

One was found in a bunch of supermarket bananas in London

A Brazilian wandering spider (João P. Burini via WikiCommons)

The world’s most venomous spider has been delivered to a south London home in a bunch of bananas.

Specialists were called in to trap the Brazilian wandering spider, which ripped its leg off in a bid to escape and left an egg sac full of thousands of baby spiders behind.

The family who received the deadly arachnid in their Waitrose online shop told the Mail on Sunday they were “too traumatised to remain in the house”, while the supermarket apologised for the “distressing” incident.

It was not the first time a Brazilian wandering spider made the long journey to the UK.

In 2005, a chef in Somerset was bitten by a stowaway that had been hiding in bananas delivered to his pub.

He was saved by anti-venom administered after a nearby zoo identified the arachnid from a picture he took on his phone before passing out.

The spiders and their eggs have also been found in bananas from a Tesco in Essex and One Stop in Staffordshire.

Where are they from?

Fortunately, it is very rare to find Brazilian wandering spiders in the UK or anywhere outside their natural habitat in South America.

They live in the forests of Costa Rica, Columbia, Peru, Brazil, and Paraguay and gain their name from the habit of moving across jungle floors at night in search of food.

In the day, they like hiding in places that are dark and moist and are known to favour piles of wood, garages, cupboards, shoes and even heaps of clothes.

The apparent tendency to hide in banana bunches – like in the latest incident – has given them the nickname “banana spider”.

Their scientific name translates as “murderess” in Greek and they are also known as the “armed spider”, because of their unusual attacking stance, and “horse stinger”.

How deadly is it?

The Guinness Book of World Records has named it the most venomous spider in the world for possessing the most active neurotoxic venom of any living spider.

The toxin PhTx3 causes extreme pain, swelling, paralysis, skin cell destruction, fatal breathing complications, heart attacks and painful erections (priapism) in men lasting up to four-hours.

Victims of a Brazilian wandering spider bite can reportedly be killed in an hour.

But few deaths occur because an effective anti-venom is available in Brazil and Guinness claims that people are killed, it is usually in children under the age of seven.

Scientists have reportedly considered investigating the use of the deadly venom as a possible ingredient for drugs treating erectile dysfunction.

What do Brazilian wandering spiders look like?

There are eight known species, with the most dangerous being the Phoneutria fera and the Phoneutria nigriventer.

All vary slightly in appearance but are known for their size, with a leg span of up to 15 cm (6 ins) and body length of up to 5 cm (2 ins).

They are covered with hair and usually dark brown in colour, with some displaying bright red hairs on their venom glands.

When Brazilian wandering spiders feel threatened, they adopt a distinctive “attacking” stance with their front legs in the air, swaying from side to side.

How do they attack?

The spiders use bites as their main form of attack but do not always deliver venom, using it only in an estimated third of bites.

They eat insects and small mammals, including other spiders, amphibians, reptiles and mice, hunting them on the ground and killing with an ambush or direct attack.